pacienco

The adjective comes first: pacienca is patient, and -ec- turns the quality into the thing you run out of. From there the family builds itself without a dictionary: pacience patiently, malpacienca impatient, malpacienco impatience. The person you are being patient with takes kun, the thing you are enduring takes pri, so havi paciencon kun la infanoj but havi paciencon pri la atendado. English speakers reach for "patient" as a hospital noun too; that one is paciento in Esperanto, a separate root, and mixing the two is a common slip in medical texts.